Wide Dynamic Range Broadband Current Mode Linear Detector Circuits for High Power Radio Frequency Power Amplifier

ABSTRACT

A power detector with a detection signal input connectable to a source of a radio frequency signal and a detected power level output has a differential amplifier detector circuit with an input connected to the detection signal input and an output corresponding to the detected power level output. A feedback network is connected to the input and the output of the differential amplifier detector circuit. A mirror circuit is connected to the differential amplifier detector circuit. A root mean square current corresponding to a power level of the radio frequency signal from the source is mirrored and integrated, with a direct current voltage level being generated therefrom and output to the detected power level output.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application relates to and claims the benefit under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 62/264,802 filed Dec.8, 2015 and entitled “WIDE DYNAMIC RANGE BROADBAND CURRENT MODE LINEARDETECTOR CIRCUITS FOR HIGH POWER RF PA,” the entire contents of which iswholly incorporated by reference herein.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND 1. Technical Field

The present disclosure relates generally to radio frequency integratedcircuits, and more particularly, to wide dynamic range broadband currentmode linear detector circuits for high power radio frequency poweramplifiers.

2. Related Art

Wireless communications systems are utilized in a variety contextsinvolving information transfer over long and short distances alike, anda wide range of modalities for addressing the particular needs of eachbeing known in the art. As a general matter, wireless communicationsinvolve a radio frequency (RF) carrier signal that is variouslymodulated to represent information/data, and the encoding, modulation,transmission, reception, de-modulation, and decoding of the signalconform to a set of standards for coordination of the same.

Many different mobile communication technologies or air interfacesexist, including GSM (Global System for Mobile Communications), EDGE(Enhanced Data rates for GSM Evolution), and UMTS (Universal MobileTelecommunications System). Various generations of these technologiesexist and are deployed in phases, with one common third generation (3G)UMTS-related modality referred to as UMTS-FDD (frequency divisionduplexing) being W-CDMA (Wideband Code Division Multiplexing). Morerecently, 4G (fourth generation) technologies such as LTE (Long TermEvolution), which is based on the earlier GSM and UMTS standards, arebeing deployed. Besides mobile communications modalities such as these,various communications devices incorporate local area data networkingmodalities such as Wireless LAN (WLAN)/WiFi. Along these lines,last-mile wireless broadband access technologies such as WiMAX(Worldwide Interoperability for Microwave Access) are also beingimplemented.

A fundamental component of any wireless communications system is thetransceiver, that is, the combined transmitter and receiver circuitry.The transceiver encodes the data as a baseband signal and modulates thebaseband signal with an RF carrier signal. Upon receipt, the transceiverdown-converts the RF signal, demodulates the baseband signal, anddecodes the data represented by the baseband signal. An antennaconnected to the transmitter converts the electrical signals toelectromagnetic waves, and an antenna connected to the receiver convertsthe electromagnetic waves back to electrical signals. Depending on theparticulars of the communications modality, single or multiple antennasmay be utilized.

Transceivers typically do not generate sufficient power or havesufficient sensitivity for reliable communications standing alone. Thus,additional conditioning of the RF signal is necessary. The circuitrybetween the transceiver and the antenna that provide this functionalityis referred to as the front end, which is understood to include a poweramplifier for increased transmission power, and/or a low noise amplifierfor increased reception sensitivity. Additionally, there may be a RFswitch that selectively connects the transmit chain (including the poweramplifier), and the receive chain (including the low noise amplifier)tot the antenna. Each band or operating frequency of the communicationssystem may have a dedicated power amplifier and low noise amplifiertuned specifically to that operating frequency.

Detecting and controlling the performance of an amplifier makes itpossible to maximize the output power while achieving optimum linearityand efficiency, and so a power detector may be integrated into the frontend circuit. The power detector is typically utilized in the transmitchain to monitor the output of the power amplifier, and generates adirect current (DC) voltage that is related to the measured power. Thisvoltage is fed back to the transceiver, which uses it for signalstrength indication. In turn, the proper gain may be set in a variablegain amplifier. A directional coupler may be connected to the output ofthe power amplifier, with one of its ports being connected to the inputof the power detector.

In order to achieve higher output power, the size of the amplifiercircuit, and in particular the transistors therefor, must be increasedfor optimal drain impedance, current handling capacity, and heatdissipation. The higher output power from the amplifier also impacts thepower detector, as a wide dynamic range is needed for detecting both lowand high output power with monotonically increasing voltage. Yet, thepush for ever-decreasing size in mobile communications devices is atodds with larger integrated circuit components needed for handlinghigher power levels and incorporating more features.

Power detectors generally fall into one of two types—diode-based andlogarithmic-based. There are several shortcomings with respect toconventional diode-based power detector circuits. Namely, the outputvoltage versus output power tends to follow a parabolic curve. Suchpower detectors also have narrow dynamic range and lack sufficientlinearity across the entire output power range. In some cases, acomplicated algorithm for baseband calibration is needed. A logarithmicpower detector can be linear across a wider power detection range, butin order to achieve this, multiple cascaded attenuation andamplification stages with a final summation amplifier is necessary.Furthermore, the circuitry is complicated, and accordingly occupies alarge footprint on the integrated circuit die. The logarithmic powerdetector also has a significantly higher current consumption for thewider power detection range, which adds to the challenges of achievinghigh power-added efficiency (PAE) of the overall power amplifiercircuit.

Accordingly, there is a need in the art for an improved non-logarithmicpower detector with wide dynamic range. Additionally, there is a needfor power detectors with minimal physical size, and capable of operationwith a variety of wireless communication modalities and the differentsignal types thereof.

BRIEF SUMMARY

Various embodiments of a power detector are disclosed. The powerdetector is non-logarithmic, and the linearity of the output voltagefrom the input power is maintained over a wide dynamic range, preferablyover 40 dB. The power detector is operational with radio frequency inputsignals from below 10 MHz to over 10 GHz. Additionally, the integratedcircuit is contemplated to occupy a footprint of less than 0.03 mm²,with less than 2 mA of current consumption. Because of its operabilityover a wide range of input signal frequencies, supply voltages, andambient temperatures, the complexity associated with basebandcalibration in wireless communications systems is substantially reduced.

According to one embodiment of the present disclosure, there is a powerdetector with a detection signal input connectable to a source of aradio frequency signal, and a detected power level output. The powerdetector may include a differential amplifier detector circuit with aninput connected to the detection signal input and an outputcorresponding to the detected power level output. Additionally, theremay be a feedback network connected to the input and the output of thedifferential amplifier detector circuit. The power detector may furtherinclude a mirror circuit that is connected to the differential amplifierdetector circuit. A root mean square current corresponding to a powerlevel of the radio frequency signal from the source may be mirrored andintegrated, with a direct current voltage level being generatedtherefrom and output to the detected power level output. The directcurrent voltage may be within a first predetermined voltage rangebetween a low end and a high end and corresponding to the power level ofthe radio frequency signal.

Also contemplated in accordance with the present disclosure is a frontend circuit with the aforementioned power detector, as well as awireless communications device that incorporates such a power detector.The present disclosure will be best understood by reference to thefollowing detailed description when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the various embodimentsdisclosed herein will be better understood with respect to the followingdescription and drawings, in which like numbers refer to like partsthroughout, and in which:

FIG. 1 a block diagram of an exemplary wireless communications devicethat may incorporate a power detector in accordance with the presentdisclosure;

FIG. 2 is a block diagram of an exemplary multi-stage power amplifiercircuit with which the disclosed power detector may be utilized;

FIG. 3 is a schematic diagram of a first embodiment of the powerdetector;

FIG. 4 is a schematic diagram of a second embodiment of the powerdetector in which a first one of the differential amplifier transistorsis connected as a diode;

FIG. 5 is a schematic diagram of a third embodiment of the powerdetector in which a second one of the differential amplifier transistorsis connected as a diode;

FIG. 6 is a schematic diagram of the power detector connected to a lowdrop out (LDO) voltage regulator;

FIG. 7 is a graph plotting output voltages from the power detector ofthe present disclosure over a frequency sweep, and includes a plot ofoutput voltages from a conventional diode-based detector by way ofcomparison;

FIG. 8 is a graph plotting the output voltage from the power detector ofthe present disclosure over an input signal power level sweep;

FIG. 9 is a graph plotting the output voltage from the power detector ofthe present disclosure over an input signal power level sweep formultiple operating frequencies;

FIG. 10 is a graph plotting the output voltage from the power detectorof the present disclosure over an input signal power level sweep formultiple operating temperatures;

FIG. 11 is a graph plotting the output voltage from the power detectorof the present disclosure over an input signal power level sweep formultiple battery supply voltages;

FIG. 12 is a graph plotting the output voltage from the power detectorof the present disclosure over a sweep of two-tone frequency spacing dQ;

FIG. 13 is a schematic diagram of a packaged front end module; and

FIG. 14 is a schematic diagram of a cross-section of the packaged frontend module shown in FIG. 13.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of the several presentlycontemplated embodiments of power detectors and radio frequency (RF)front end circuits utilizing the same, and are not intended to representthe only form in which the disclosed power detectors may be developed orutilized. The description sets forth the functions and features inconnection with the illustrated embodiments. It is to be understood,however, that the same or equivalent functions may be accomplished bydifferent embodiments that are also intended to be encompassed withinthe scope of the present disclosure. It is further understood that theuse of relational terms such as first and second and the like are usedsolely to distinguish one from another entity without necessarilyrequiring or implying any actual such relationship or order between suchentities.

FIG. 1 illustrates a simplified wireless communications device 10 inwhich various embodiments of the power detector in accordance with thepresent disclosure may be incorporated. In various embodiments, thewireless communications device 10 can be a cellular telephone. However,the low noise amplifier circuit may be utilized in any wireless devicewith signal reception capabilities. The wireless communications device10 illustrated in FIG. 1 is intended to be a simplified example of acellular telephone and to illustrate one of many possible applicationsin which the low noise amplifier circuit can be implemented. One havingordinary skill in the art will understand the operation of a cellulartelephone, and, as such, implementation details are omitted.

The wireless communications device 10 includes a baseband subsystem 12,a transceiver 14, and a front end module 16. Although omitted from FIG.1, the transceiver 14 includes modulation and upconversion circuitry forpreparing a baseband information signal for amplification andtransmission, and includes filtering and downconversion circuitry forreceiving and downconverting a radio frequency signal to a basebandinformation signal to recover data. The details of the operation of thetransceiver 14 are known to those skilled in the art.

The baseband subsystem 12 generally includes a processor 18, which canbe a general purpose or special purpose microprocessor, memory 20,application software 22, analog circuit elements 24, and digital circuitelements 26, connected over a system bus 28. The system bus 28 caninclude the physical and logical connections to couple theabove-described elements together and enable their interoperability.

An input/output (I/O) element 30 is connected to the baseband subsystem12 over a connection 32, a memory element 34 is coupled to the basebandsubsystem 12 over a connection 36 and a power source 38 is connected tothe baseband subsystem 12 over connection 40. The I/O element 30 caninclude, for example, a microphone, a keypad, a speaker, a pointingdevice, user interface control elements, and any other device or systemthat allows a user to provide input commands and receive outputs fromthe wireless communications device 10.

The memory 20 can be any type of volatile or non-volatile memory, and inan embodiment, can include flash memory. The memory element 34 can bepermanently installed in the wireless communications device 10, or canbe a removable memory element, such as a removable memory card.

The power source 38 can be, for example, a battery, or otherrechargeable power source, or can be an adaptor that converts AC powerto the correct voltage used by the wireless communications device 10. Inan embodiment, the power source can be a battery that provides a nominalvoltage output of approximately 3.6 volts (V). However, the outputvoltage range of the power source can range from approximately 3.0 to6.0 V. As will be appreciated, the power source 38 or battery may outputa voltage level higher than what is needed by the components of thewireless communications device 10 at full charge, and gradually reducethe voltage level as it is discharged. Accordingly, there may be aseparate central power regulator 42 that stabilizes or regulates thevoltage level, then distributes the same to each of the components ofthe wireless communications device 10. Each of the subsystems and/orcomponents may be connected to the central power regulator 42 over apower bus 44. Alternatively, each subsystem may have a separate powerregulation circuit, as different components may have varying sourcepower stability requirements.

The processor 18 can be any processor that executes the applicationsoftware 22 to control the operation and functionality of the wirelesscommunications device 10. The memory 20 can be volatile or non-volatilememory, and in an embodiment, can be non-volatile memory that stores theapplication software 22.

The analog circuit elements 24 and the digital circuit elements 26include the signal processing, signal conversion, and logic that convertan input signal provided by the I/O element 30 to an information signalthat is to be transmitted. Similarly, the analog circuit elements 24 andthe digital circuit elements 26 include the signal processing, signalconversion, and logic that convert a received signal provided by thetransceiver 14 to an information signal that contains recoveredinformation. The digital circuit elements 26 can include, for example, aDigital Signal Processor (DSP), a Field Programmable Gate Array (FPGA),or any other processing device. Because the baseband subsystem 12includes both analog and digital elements, it is sometimes referred toas a mixed signal circuit.

The front end module 16 is generally comprised of components belongingto a transmit signal chain, components belonging to a receive signalchain, and a switch 46. For purposes of simplification, the transmitsignal chain is generally represented by a power amplifier 48, while thereceive signal chain is generally represented by a low noise amplifier50. The switch 46 interconnects the power amplifier 48 and the low noiseamplifier 50 to an antenna 52. The front end module 16 depicted in FIG.1 is understood to be for a single wireless operating mode, and thosehaving ordinary skill in the art will appreciate that a conventionalwireless communications device 10 has multiple wireless operating modesconforming to different standards. Accordingly, there may be multiplefront end modules 16 particularly configured for each operating mode, orone front end module 16 with multiple constituent components for eachoperating mode. Along these lines, these different operating modes mayutilize more than one antenna at a time (diversity mode operation), sothe single antenna 52 is presented by way of example only and not oflimitation.

As discussed earlier, monitoring the power levels of the signalgenerated by the power amplifier 48 helps improve its performance, andaccordingly, the present disclosure contemplates various power detectorsto this end. With reference to the schematic diagram of FIG. 2, thepower amplifier 48 may be comprised of three stages, including a firstamplifier stage 54 a, a driver amplifier stage 54 b, and a poweramplifier stage 48 c.

A radio frequency signal generated by the transceiver 14 is passed to apower amplifier input 56 and sequentially amplified in stages to beoutput from a power amplifier output 58. The first amplifier stage 54 ais typically a voltage amplification stage, with ensures that the radiofrequency signal from the transceiver 14 has adequate voltage for thesubsequent amplification stages. The driver amplifier stage 54 b isunderstood to increase current for further power amplification by thepower amplifier stage 54 c.

The first amplifier stage 54 a may include an input matching network 60that impedance matches the power amplifier 48 to the transceiver 14.Along these lines, the driver amplifier stage 54 b may include a firstinter-stage matching network 62, which impedance matches the driveramplifier stage 54 b to the first amplifier stage 54 a. Additionally,the power amplifier stage 54 c includes a second inter-stage matchingnetwork 64 that similarly impedance matches the power amplifier stage 54c to the driver amplifier stage 54 b. The output of the power amplifierstage 54 c is connected to an output matching network 66 that impedancesmatches the power amplifier stage 54 c to the antenna 52 and/or theswitch 46 mentioned earlier.

In accordance with various embodiments of the present disclosure,measurements of the power levels at either or both the power amplifierinput 56 and the power amplifier output 58 may be taken. Thus, the poweramplifier 48 may include a first directional coupler 68 with an inputport 70 a connected to the power amplifier input 56, a transmitting port70 b connected to the input matching network 60, and a coupled ordetector port 70 c connected to an input power detector 72, which mayalso include a power limiter. As will be described in further detailbelow, a power detector is understood to generate a direct current (DC)voltage level that corresponds to the power level of an input RF signal.In this regard, the output of the input power detector 72 may beconnected to a gain control circuit that may be implemented in, forexample, the transceiver 14.

Various embodiments of the present disclosure also contemplate measuringthe power levels output from the power amplifier 48, and accordinglythere may be an output power detector 74. There is likewise a seconddirectional coupler 76 that has an input port 78 a connected to theoutput of the output matching network 66 and the power amplifier stage54 c, as well as a transmitting port 78 b connected to the poweramplifier output 58. A coupled or detector port 78 c is connected to theoutput power detector 74. Like the input power detector 72, the outputpower detector 74 generates a DC voltage corresponding to the powerlevel of the RF signal as amplified by the first amplifier stage 54 a,the driver amplifier stage 54 b, and the power amplifier stage 54 c,which is passed to the antenna 52. The DC voltage output from the outputpower detector 74 is passed to a gain control circuit.

While some embodiments of the disclosed power detectors 72, 74 mayspecifically reference the output power detector 74, this is by way ofexample only and not of limitation. The features of the output powerdetector 74 may find equal utility and applicability in the input powerdetector 72, and may be readily incorporated without departing from thescope of the present disclosure. Along these lines, while the presentdisclosure makes reference to the use of the power detectors for thepower amplifier 48, it will also be appreciated that similar powerdetectors may be utilized for the low noise amplifier 50 and inputsignals received from the antenna 52.

The bias voltage of each of the aforementioned amplifier stages 54 a-54c may be provided by a low dropout (LDO) voltage regulator 80, which isconnected to the power source 38, and maintains the output voltage at aset value. The LDO voltage regulator 80 is understood to provide asteady voltage supply to the power detectors 72, 74 as well.

Referring now to the schematic diagram of FIG. 3, a first embodiment ofthe power detector 74 has a detection signal input 82 that isconnectable to a source of a RF signal, which in accordance with theforegoing, may be the power amplifier 48. Additionally, the powerdetector 74 has a detected power level output 84, which as discussedabove, may be connected to an amplifier gain control circuit.

The power detector 74, which operates in current mode, includes adifferential amplifier detector circuit 86 with an input that isconnected to the detection signal input 82, and an output that isconnected to the detected power level output 84. In further detail, thedifferential amplifier detector circuit 86 has a first differentialamplifier transistor MN1 with a gate that corresponds to one of thedifferential inputs, as well as a second differential amplifiertransistor MN2 likewise with a gate that correspond to another one ofthe differential inputs. A negative feedback resistor R3 is connectedbetween the first differential amplifier transistor MN1 and the seconddifferential amplifier transistor MN2. It is understood that thenegative feedback resistor R3 controls the gain of the differentialamplifier detector circuit 86.

The gate of the first differential amplifier transistor MN1 is connectedto the detection signal input 82 via a resistor R4, while the gate ofthe second differential amplifier transistor MN2 is connected to thedetection signal input 82 via a resistor R6. The gate of the transistorMN1 is also connected to a resistor R7, as well as a resistor R6. Inthis regard, the resistors R4, R5, R6, and R7 are understood to define afeedback network 88 that stabilizes the output DC voltage from thedifferential amplifier detector circuit 86 across semiconductor diefabrication process variations, power supply voltage variations, andtemperature variations.

The power detector 74 also includes a mirror circuit 90 that isconnected to the differential amplifier detector circuit 86.Specifically, the mirror circuit 90 has a first mirror transistor MP1that is connected to the first differential amplifier transistor M1, anda second mirror transistor MP2 that is connected to the seconddifferential amplifier transistor M2. The mirror transistors MP1 and MP2are controlled by an enable transistor 92, which is connected to therespective gates of the first and second mirror transistors MP1 and MP2.The mirror transistors MP1 and MP2, as well as the enable transistor 92,are biased with voltage from a power supply input Vdd, as are thedifferential amplifier transistors MN1 and MN2 selectively via themirror transistors MP1 and MP2.

The power detector 74 is understood to mirror and integrate theroot-mean-square (RMS) current, which tracks the input power of the RFinput signal. The RMS current is charged injected into the capacitor,and the DC voltage corresponding to the input power of the RF inputsignal is generated. The aforementioned first and second mirrortransistors MP1 and MP2 are contemplated to increase the dynamic rangeof detection, particularly at low forward power.

The DC voltage generated by the power detector 74 may be within apredetermined voltage range bounded by a low end and a high end. At thelow end, the DC voltage may be greater than zero, though some gaincontrol circuits expect the low end voltage to begin from zero. In thisregard, the power detector 74 further includes a subtractor circuit 94that reduces the output DC voltage by a predetermined amount such thatthe low end of the voltage range becomes zero. The subtractor circuit 94may be tuned to adjust the overall gain and the linear response of thepower detector 74. The output of the subtractor circuit 94 may also beconnected to an electrostatic discharge circuit 96.

Referring to the alternative embodiment of the power detector 74 shownin FIG. 4, it is also possible to connect the first differentialamplifier transistor M1 in a diode configuration, which involvesconnecting the gate to the drain, as shown in an interconnection node97. FIG. 5 illustrates yet another embodiment of the power detector 74in which the second differential amplifier transistor M2 is likewiseconnected in a diode configuration, as shown in an interconnection node98. In all other respects, however, the embodiments of the powerdetector 74 shown in FIGS. 4 and 5 are identical to the embodiment shownin FIG. 3.

With reference to the schematic diagram of FIG. 6 yet another embodimentof the present disclosure is directed to utilizing a small form factormonolithic LDO voltage regulator 80, which is connected to the voltagesupply input Vdd of the output power detector 74. The LDO voltageregulator 80 includes an operational amplifier 102. A voltage supplyterminal VDD 103 is connected to the power source 38, which ispreferably a battery. The operational amplifier 102 includes a referenceinput 104. A reference voltage setting resistor R10 is connected to thereference input 104 and to a current reference I_(REF) 106.

The LDO voltage regulator 80 further includes a feedback circuit 108comprised of a resistor R4 and a resistor R3. A junction 110 between theresistor R9 and the resistor R8 corresponds to the output of the LDOvoltage regulator 80. The particular values of the resistors R8 and R9of the feedback circuit 108, as well as the reference voltage settingresistor R10, together with the current reference I_(REF) 106 areunderstood to define the output voltage of the LDO voltage regulator 80.As is expected of the LDO voltage regulator 80, there is also a passcircuit 112, specifically a pass transistor MP-3 that is connected tothe voltage supply terminal VDD 103. The LDO voltage regulator 80generates a stable voltage supply to the power detector 74.Additionally, this ensures that there is no breakdown, and that there isless variation over a wide range of battery output voltages.

Referring to the graph of FIG. 7, there is illustrated in a first plot113 a the simulated DC voltage that is generated by the power detector74 over an RF input signal power sweep from −5 dB to 40 dBm. A secondplot 113 b, by comparison, shows the simulated DC voltage levelsgenerated by a conventional diode power detector with the samedirectional coupler 76. As illustrated, the power detector 74 of thepresent disclosure exhibits a significantly wider dynamic power range.

The graph of FIG. 8 plots the simulated output DC voltage from the powerdetector 74 over varying battery supply voltages that are regulated bythe LDO voltage regulator 80. As shown, with the embodiment of the powerdetector 74 and the LDO voltage regulator 80 presented in FIG. 6, thereis little different in simulated DC voltage output at different batteryvoltages from 3.6V to 5V.

The graph of FIG. 9 plots the simulated output DC voltage generated bythe power detector 74 for varying operating frequencies from 1.5 GHz to8 Ghz over an RF input signal power range from 0 dBm to 40 dBm. As shownin plot point m31 for an operating frequency of 1.5 GHz, with the RFinput signal power of 24.739 dBm, the power detector 74 outputs a DCvoltage of 0.870 V. Further, plot point m32 shows that for an operatingfrequency of 8 GHz, with the RF input signal with a power 22.4417 dBm,the power detector 74 outputs a DC voltage of 0.912 V. Accordingly,there is understood to be minimal voltage change over a wide frequencyrange.

Referring to the graph of FIG. 10, the power detector 74 is alsounderstood to operate consistently over a wide ambient temperaturerange. Specifically, plots of the simulated output DC voltage based uponvarying RF input signal power levels from 0 dBm to 40 dBm are shown formultiple ambient temperatures, from −40 degrees Celsius, −20 degreesCelsius, and 120 degrees Celsius. For example, for an RF input signalpower of 27.789 dBm at an ambient temperature of 120 degrees Celsiusshown in plot point m39, the DC output voltage is 0.975 V. Additionally,for an RF input signal power of 25.775 at an ambient temperature of −40degrees Celsius shown in plot point m40, the DC output voltage is acomparable 0.994 V. Along the same lines, for an RF input signal powerof 35.8 dBm at an ambient temperature of 120 degrees Celsius shown inplot point m41, the DC output voltage is 1.394. A similar output powerlevel of 33.757 dBm but at an ambient temperature of −20 degrees Celsiusyields a comparable 1.339 V DC output voltage.

The graph of FIG. 11 plots the simulated DC output voltage from thepower detector 74 over different battery supply voltages ranging from3.6V to 5V, and operating frequencies ranging from 1.5 GHz to 10 GHz. Asshown, there is minimal variation over different supply voltages andoperating frequencies.

The graph of FIG. 12 plots the simulated DC output voltage from thepower detector 74 of the present disclosure over different two-tonefrequency spacing (dQ). In further detail, the RF input signal power is30 dBm, with a 3 dB bandwidth of greater than 500 MHz. It is expresslycontemplated that the power detector 74 may be utilized for peakenvelope power measurements for wide band digital and analog modulatedsignals.

FIG. 13 is a schematic diagram of an embodiment of a packaged radiofrequency communications module 114, while FIG. 14 is a schematicdiagram of a cross-section of the packaged radio frequencycommunications module 114 taken along axis A-A of FIG. 13. The packagedradio frequency communications module 114 includes an integrated circuitor die 116, surface mount components 118, wire bonds 120, a packagesubstrate 122, and an encapsulation structure 124. The package substrate122 includes pads 126 formed from conductors disposed therein.Additionally, the die 116 includes pads 128, and the wire bonds 120 areused to electrically connect the pads 128 of the die 116 to the pads 126of the package substrate 122.

The die 116 includes the power amplifier 48, the power detector 74 ofthe present disclosure, and the LDO voltage regulator 80 formed therein.These components on the die 116 are understood to be as described above,and may be fabricated with complementary metal oxide semiconductor(CMOS) processes, as well as the silicon germanium (SiGe) process, thesilicon-on-insulator (SOI) process, gallium arsenide (GaAs),heterojunction bipolar transistor (HBT) processes, and so forth. It isexpressly contemplated that the circuitry of the power detector 74itself occupies a footprint of less than 0.03 mm² on the die 116.

The die 116 is mounted to the package substrate 122 as shown, though itmay be configured to receive a plurality of additional components suchas the surface mount components 118. These components include additionalintegrated circuits as well as passive components such as capacitors,inductors, and resistors.

As shown in FIG. 13, the packaged radio frequency communications module114 is shown to include a plurality of contact pads 130 disposed on theside of the packaged radio frequency communications module 114 oppositethe side used to mount the die 116. Configuring the packaged radiofrequency communications module 114 in this manner can aid in connectingthe same to a circuit board of the wireless communications device 10.The example contact pads 130 can be configured to provide radiofrequency signals, bias signals, power low voltage(s) and or power highvoltage(s) to the die 116 and/or the surface mount components 118. Theelectrical connections between the contact pads 130 and the die 116 canbe facilitated by connections 132 through the package substrate 122. Theconnections 132 can represent electrical paths formed through thepackage substrate 122, such as connections associated with vias andconductors of a multilayer laminated package substrate.

In some embodiments, the packaged radio frequency communications module114 can also include or more packaging structures to, for example,provide protection and/or to facilitate handling of the packaged radiofrequency communications module 114. Such a packaging structure caninclude overmold or encapsulation structure 124 formed over the packagesubstrate 122 and the components and die(s) disposed thereon.

It will be understood that although the packaged radio frequencycommunications module 114 is described in the context of electricalconnections based on wire bonds, one or more features of the presentdisclosure can also be implemented in other packaging configurations,including, for example, flip-chip configurations.

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the power detectors and RFfront end circuits incorporating the same, and are presented in thecause of providing what is believed to be the most useful and readilyunderstood description of the principles and conceptual aspects. Noattempt is made to show details with more particularity than isnecessary, the description taken with the drawings making apparent tothose skilled in the art how the several forms of the present disclosuremay be embodied in practice.

What is claimed is:
 1. A power detector with a detection signal inputconnectable to a source of a radio frequency signal, and a detectedpower level output, the power detector comprising: a differentialamplifier detector circuit with an input connected to the detectionsignal input, and an output corresponding to the detected power leveloutput; a feedback network connected to the input and the output of thedifferential amplifier detector circuit; and a mirror circuit connectedto the differential amplifier detector circuit, a root mean squarecurrent corresponding to a power level of the radio frequency signalfrom the source being mirrored and integrated, with a direct currentvoltage level being generated therefrom and output to the detected powerlevel output, the direct current voltage being within a firstpredetermined voltage range between a low end and a high end andcorresponding to the power level of the radio frequency signal.
 2. Thepower detector of claim 1 further comprising a subtractor circuitconnected to the output of the differential amplifier detector circuit,the direct current voltage level corresponding to the power level of theradio frequency signal being reduced by a predetermined amount to reducethe first predetermined voltage range to have a low end of zero.
 3. Thepower detector of claim 1 wherein the differential amplifier detectorcircuit includes a first differential amplifier transistor and a seconddifferential amplifier transistor, a gate of each of the firstdifferential amplifier transistor and the second differential amplifiertransistor corresponding to the input of the differential amplifierdetector circuit.
 4. The power detector of claim 3 wherein the firstdifferential amplifier transistor is connected in a diode configuration.5. The power detector of claim 3 wherein the second differentialamplifier transistor is connected in a diode configuration.
 6. The powerdetector of claim 3 wherein the mirror circuit includes a first mirrortransistor connected to the first differential amplifier transistor, anda second mirror transistor connected to the second differentialamplifier transistor.
 7. The power detector circuit of claim 1 furthercomprising an electrostatic discharge circuit connected to the output ofthe differential amplifier detector circuit.
 8. A radio frequency frontend circuit connectable to a source of a radio frequency signal, theradio frequency front end circuit comprising: a circuit outputconnectable to a radio frequency signal destination; an amplifiercircuit implemented and including input and an output, the input beingconnected to a source of a radio frequency signal; a power detectorincluding a differential amplifier circuit with a feedback network and amirror circuit connected thereto, the differential amplifier circuitincluding an input connected to the output of the amplifier circuit, anoutput corresponding to the circuit output, a root mean square currentcorresponding to a power level of the radio frequency signal from thesource being mirrored and integrated by the power detector to generate adirect current voltage level output to the circuit output, the directcurrent voltage being within a first predetermined voltage range betweena low end and a high end and corresponding to the power level of theradio frequency signal; and a coupler having a input port connected tothe output of the amplifier circuit, a detector port connected to theinput of the power detector, and a transmitted port connected to thecircuit output.
 9. The front end circuit of claim 8 further comprising alow drop out voltage regulator connected to a respective power supplyinput of the amplifier circuit and the power detector, and outputs apredetermined voltage from a variable voltage electrical power source.10. The front end circuit of claim 9 wherein the variable voltageelectrical power source is a battery.
 11. The front end circuit of claim8 wherein the amplifier circuit is a power amplifier, the radiofrequency signal destination is an antenna, and the source of the radiofrequency signal is a transceiver circuit.
 12. The front end circuit ofclaim 8 wherein the amplifier circuit is a low noise amplifier, theradio frequency signal destination is a transceiver circuit, and thesource of the radio frequency signal is an antenna.
 13. The front endcircuit of claim 8 further comprising a subtractor circuit connected tothe output of the differential amplifier detector circuit, the directcurrent voltage level corresponding to the power level of the radiofrequency signal being reduced by a predetermined amount to reduce thefirst predetermined voltage range to have a low end of zero.
 14. A radiofrequency communications device comprising: a transceiver configured toprocess radio frequency signals; an antenna configured to facilitatetransmission and reception of the radio frequency signals; an amplifierconnected to the transceiver and the antenna and including an input andan output; and a power detector including a differential amplifiercircuit with a feedback network and a mirror circuit connected thereto,the differential amplifier circuit including an input connected to theoutput of the amplifier circuit, an output corresponding to the circuitoutput, a root mean square current corresponding to a power level of theradio frequency signal from the source being mirrored and integrated bythe power detector to generate a direct current voltage level output tothe circuit output, the direct current voltage being within a firstpredetermined voltage range between a low end and a high end andcorresponding to the power level of the radio frequency signal.
 15. Theradio frequency communications device of claim 14 further comprising adirectional coupler with an input port connected to the output of theamplifier, a detection port connected to an input of the power detector,and a transmission port connected to a selected one of the antenna andthe amplifier.
 16. The radio frequency communications device of claim 15wherein the amplifier is a low noise amplifier with the transmissionport of the directional coupler being connected to the transceiver andthe input of the amplifier being connected to the antenna.
 17. The radiofrequency communications device of claim 15 wherein the amplifier is apower amplifier with the transmission port of the directional couplerbeing connected to the antenna and the input of the amplifier beingconnected to the transceiver.
 18. The radio frequency communicationsdevice of claim 14 wherein the differential amplifier of the powerdetector includes a first differential amplifier transistor and a seconddifferential amplifier transistor.
 19. The radio frequencycommunications device of claim 18 wherein the first transistor isconnected in a diode configuration.
 20. The radio frequencycommunications device of claim 18 wherein the second transistor isconnected in a diode configuration.
 21. The radio frequencycommunications device of claim 18 wherein the mirror circuit includes afirst mirror transistor connected to the first differential amplifiertransistor, and a second mirror transistor connected to the seconddifferential amplifier transistor.
 22. The radio frequencycommunications device of claim 14 further comprising a subtractorcircuit connected to the output of the differential amplifier detectorcircuit, the direct current voltage level corresponding to the powerlevel of the radio frequency signal being reduced by a predeterminedamount to reduce the first predetermined voltage range to have a low endof zero.